Diamond bit



c. L. HEATH ET AL Oct. 3, 1939. Q

' Q DIAMOND BIT Filed Jan. 12, 1939 g g I gvENToRs BY M 6% MW ATTORNEY SPatented Oct. 3, 1939 I UNITED STATES PATENT OFFICE DIAMOND BITApplication January 12, 1939, Serial No. 250,469

9 Claims.

Our invention is directed to improvements in diamond bits and has forone of its objects the provision of a diamond bit of improved construction.

Diamond core bits as heretofore constructed have consisted of a bitblank with an alloy cast on the exterior of the end of the same, theface of this casting or matrix being studded with cutting stones, suchas commercial diamonds, which are embedded in the .alloy in the castingoperation, and provide the cutting face or surface of the bit. The bitis hollow and the inner wall of the annular member or matrix, adjacentthe outer end thereof, is lined with cutting stones also. In themanufacture of such bits the diamonds and the bit blank are set up in asuitable mold and molten metal flowed into the mold. In order that thediamonds may not be.

injured in the casting operation it is necessary to employ a metal oralloy for the matrix which has a relatively low melting point, that is,a melting point below that of steel, for example. While this protectsthe diamonds from being injured in the casting operation, itnecessitates the use of a relatively soft metal for the matrix, so thatwhen the bit is in use the core of the ore being drilled, as it passesthrough the bit, wears away the matrix and undercuts the diamonds, sothat they become dislodged. This defect is well recognized by thosefamiliar with this art and is overcome by our invention.

Broadly speaking, our invention provides a core bit wherein that part ofthe bit which previously is readily undercut is of a hard metal, therebyproviding a bit which has a much longer life than prior bits and inwhich the diamonds are not readily dislodged.

We have shown an embodiment of our invention in the accompanyingdrawing, in which:

Fig. 1 is a sectional elevational view of the bit; and

Fig. 2 is an exploded view of the bit blank and hard metal ring enteringinto our construction.

Referring to the drawing in detail: 2 designates the bit blank. This bitblank may be of steel or other metal desired. The shank of the bit blankis threaded, as shown at l, as is usual.

The head of this bit blank is flared internally, as seen at 6, and thisflared interior is provided with locking shoulders 8. The wall of thehead of the bit blank is provided with apertures in which also functionas locks, as will be brought out hereinafter.

Within the flared portion of the head of the bit blank is the matrix i2for the diamonds ll or other cutting elements. The matrix, as will beunderstood, is an annulus, and the cutting elements I are not onlydisposed inthe face of this annulus but about the inner wall of theannulus adjacent the workingface or forward end of the bit, as shown atIS. The matrix I2, which is a casting, is composed of any of the metalsor alloys commonly employed in the diamond bit industry.

Adjacent the mouth or forward end of the bit, we provide a preformedhard metal ring i8, for example, a. steel ring. This ring is embedded inthe matrix l2 and lies Just within the end of the matrix just above thecutting stones IS with which the mouth of the bit is provided, as aboveexplained.

In manufacturing our bit, the bit blank 2, the ring I! and the stones llare assembled in a suitable mold, and the metal of the matrix I! pouredthereinto, the metal flowing about the cutting stones and about the hardmetal ring i8 to embed the same. It will be appreciated, also, that themetal flows into the locking apertures l0 and that these together withthe locking shoulders 8 securely lock the matrix to the bit blank.

It will be appreciated from all of the foregoing that the preformed hardmetal ring l8 will reinforce the matrix and prevent undercutting anddislodgment of the diamonds or other cutting elements, when the bit isbeing used, the core of the ore being drilled, as the same passesthrough the hollow matrix, being kept out of contact with the matrixadjacent the nose of the bit by the ring.

It is to be understood that changes may be made in the details ofconstruction and arrangement of parts above described without departingfrom the spirit and scope of our invention.

What we claim is:

1. A core bit comprising in combination a bit blank, a matrix in theform of an annulus carried by the bit blank, cutting stones in the faceof the matrix, and a preformed hard metal ring embedded in theinner wallof the matrix adjacent the working face of the bit.

2. A core bit comprising in combination a bit blank. a matrix in theform of an annulus carried within the blank, cutting stones in the innerwall of the matrix. and a preformed hard metal ring embedded in theinner wall of the matrix adjacent said stones.

3. A core bit comprising in combination a bit blank, an annular matrixcast within the blank, cutting stones embedded in the inner wall of thematrix, and a preformed hard metal ring embedded in the inner wall 01'the matrix adjacent said stones.

4. A core bit comprising in combination a hollow bit blank, lockingshoulders formed on the interior of the'head oi. the bit blank, the wall01! the bit blank being provided with locking apertures, a cast matrixwithin the bit blank and held against dislodgment by said shoulders andapertures and cutting stones embedded in the face of said matrix.

5.. A core bit comprising in combination a hollow bit blank, the head ofwhich is outwardly flared internally, and a diamond-carrying annularmatrix cast within the flared portion of the bit blank.

6. A core bit comprising in combination a hollow bit blank, the head ofwhich is outwardly flared internally, said flared portion of the blankbeing provided with looking shoulders, a matrix cast within theoutwardly flared head of the blank, and held therein by said lockingshoulders, and cutting stones embedded in the outer end of the matrix.

7. A core bit comprising in combination a hollow bit blank, the head ofwhich is outwardly flared internally, said flared portion 01 the blankbeing provided with looking shoulders, a matrix cast within theoutwardly flared head of the-blank and held therein by the said lockingshoulders, cutting stones embedded in the outer end of the matrix, and ametal ring of a metal harder than the matrix embedded in the matrixinteriorly thereof.

8. A core "bit comprising in combination a bit blank, a cast matrix withcutting stones embedded therein carried by the bit blank, and apreformed ring of a material harder than the material of the matrixembedded in the matrix interiorly thereof.

9. A core bit comprising in combination a bit blank, a matrix, providedby a cast metal annulus and having cutting stones embedded in its outerface and in its inner wall, secured to said bit blank, and a preformedring of a metal harder than that of the matrix embedded in the innerwall of the matrix adjacent the outer end of the matrix and constitutinga lining ring for the matrix.

CLARENCE L. HEATH. ELLSWOR'I'H B. SHERWOOD.

